JP3321252B2 - Transmission line fault section detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a faulty section of a transmission line , and more particularly to an apparatus for detecting a faulty section of a transmission line by simply combining the outputs of a plurality of magnetic sensors arranged at predetermined positions with respect to the transmission line, as in a multi-circuit tower. Even when the effect of each transmission line load current cannot be completely canceled, the effect of each transmission line load current can be removed and the fault current can be reliably detected , and the fault area can be detected.
The present invention relates to a transmission line fault section detection device that can determine the interval .

[0002]

2. Description of the Related Art As a method of detecting a faulty section of a transmission line, a fault current is monitored and measured by a ground fault or short-circuit current detector provided at an appropriate portion (for example, a steel tower) of the transmission line, and adjacent lines are measured. A method of comparing phases of fault currents obtained at measurement points and determining a phase inversion section of the fault current as a fault section is widely known and implemented. For example, in Japanese Patent Application Laid-Open No. Hei 1-209387 proposed by the present applicant, a fault current (a short-circuit current or a zero-phase current in case of a ground fault) is measured at an appropriate position on a transmission line, and a fault is detected at an adjacent measurement position. A method of determining a phase inversion section of a current as a failure section is proposed.

[0003] The measurement of the zero-sequence current at the time of a ground fault is performed, for example, by using a pair of magnetic sensors each having a coil wound around an elongated iron core as described in Japanese Utility Model Publication No. 4-24455. Above and below the polygon connecting the positions, the longitudinal direction of the iron core is arranged so as to be perpendicular to the power line and horizontal, and the respective coils are differentially connected. Alternatively, it can be performed by setting the magnetic sensor constants such as the material, length, cross-sectional area, and number of coil turns of the iron core, and the installation position (distance from each transmission line) so as to be a minute value.

[0004]

In the above-described method for detecting a fault zone by measuring the zero-phase current and comparing the phases, the constant of each magnetic sensor for measuring the zero-phase current and the distance from each transmission line, that is, the installation position are adjusted. Therefore, it is necessary to make the combined output during normal operation zero, but except for the specific four-circuit tower where the arm length and the arm interval of the tower suspending the transmission line are equal. It is extremely difficult to make the output zero. Especially with multi-circuit towers, it is virtually impossible to reduce the combined output to zero even if the number of installed magnetic sensors is increased. There is a problem that it is practically difficult to accurately detect a section.

[0005] Even in the case of a four-circuit tower, if the lower line is at both ends NGR (neutral point resistance ground) and the upper line is a single-ended NTR system power line, if a failure occurs in the upper line, as described later, In some cases, the phases of the detection output waveforms of the zero-phase current measurement magnetic sensor are all in phase, and there is a problem that a failure section cannot be detected by phase comparison.

[0006] An object of the present invention is to solve the above-mentioned problem by performing waveform processing even when the combined output of a plurality of magnetic sensors provided for measuring fault current such as zero-phase current and short-circuit current cannot be reduced to zero. Accordingly, residual load current component offset the easy fault current only extraction City, to be et al., the peak value of the fault current in the adjacent detection point was detected and compared both phase, at least one of based upon the change in the reference value or more, even in the multi-circuit併架towers, it is to provide a that equipment to enable detection of an accurate fault section.

[0007] transmission line fault segment detection device of the present invention, a fault current detection means arranged for each appropriate intervals along the transmission line, each output signal of said fault current detecting means respectively N /
Each output signal in the normal state of the transmission line cancels out a delay means for delaying two cycles (N is a positive integer) and each output signal of the fault current detection means and a corresponding signal delayed by N / 2 cycles. To generate a fault current signal
That and a means.

[0008] Further, in order to detect a transmission line fault section, the phase and level of fault current are measured at measurement points set at predetermined intervals along the transmission line, and faults obtained at two adjacent measurement points are measured. Both the phase and the level of the current are compared, and when the difference between the two is greater than or equal to a predetermined reference value, the two measurement points adjacent to each other are determined to be a failure zone. For this purpose, ground fault current detecting means and short-circuit current detecting means arranged at measurement points set at appropriate intervals along the transmission line, and output signals of the ground fault current detecting means and short-circuit current detecting means are output. Delay means for delaying each of N / 2 cycles (N is a positive integer), and N / N
Means for adding and subtracting each corresponding signal delayed by two cycles to generate and output a ground fault current and a short-circuit current signal so that each output signal in a normal state of the transmission line is canceled; Means for calculating the difference between the phase and the peak value of the ground fault current and the short-circuit current signal, and the phase and the peak value of the ground fault current and the short-circuit current signal at a detection point adjacent thereto, respectively, Means for determining a fault section between the two adjacent detection points when at least one of the differences is greater than a predetermined reference value, and for measuring a phase of the fault current signal.
Phase measurement means, wherein the phase measurement means
Current zero-cross detector that detects the zero-cross point of an elephant current signal
And voltage zero cross detection to detect the zero cross point of the voltage signal
Divides the output pulse of the detector and the voltage zero cross detector
And a first reset by each output of said divider
A counter and the respective outputs of the frequency divider determine the first clock.
Counter reset in the middle of the timer reset timing.
2 counter and a clock applied to the first and second counters.
A clock oscillator for supplying a pulse, and the current zero crossing
The signal read out in response to the zero crossing point detection signal of the detector.
The larger of the count values of the first and second counters
Value selector that selects as the phase signal of the current to be measured
It equipped with a door.

[0009]

[Action] The output signal and the N / 2-cycle delayed signal of the fault current detecting means, wherein the output signal of the normal transmission line is added or subtracted so as to cancel out, the fault current detected during the normal power lines Even if a load current component is included in the output signal of the means , it is possible to remove the influence of the load current component and separate and extract only the fault current component.

In order to detect a fault section, the phase and peak values of the ground fault current and the short-circuit current signal at one detection point set along the transmission line and the ground fault current at a detection point adjacent thereto are determined. And the difference between the phase and the peak value of the short-circuit current signal is calculated, and it is determined whether at least one of the differences exceeds a predetermined reference value. It is possible to reliably detect a failed section that has not been detected.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 4 is a schematic diagram showing an example of a state in which various sensors used in the present embodiment are mounted on a power transmission tower. The power lines R1, S1, T1, U1, V1, W1 are connected to the respective arms of the tower 8 via insulators.
1, R2, S2, T2, U2, V2, W2 are suspended,
An overhead ground wire 38 is laid at the top. Magnetic sensors for measuring zero-phase current (hereinafter referred to as ground fault sensors) 11 to 1
Reference numeral 3 is Y-connected, and the added outputs of the paired sensors 11 and 12 and 12 and 13 are supplied to a multiplexer 29 via A / D converters (not shown) and filters 24 and 25. Short-circuit current detection sensors (hereinafter, referred to as short-circuit sensors) 14, 15 and a voltage sensor 16 for phase reference / trip monitoring are also provided to a multiplexer 29 via corresponding A / D converters (not shown) and filters 26 to 28, respectively. Supplied.

The filter serves to remove noise components in the sensor output.

In the case of a four-circuit tower, for example, as shown in FIG. 4, each of these sensors 11 to 13 is connected to a corresponding transmission line. The short-circuit sensors 14 and 15 are positioned outside the square, and the direction of the longitudinal axis of the iron core is V.
1, the V2 phase or the S1, S2 phase electric wires can be arranged so that their extension lines intersect with the electric wires (see Japanese Utility Model Publication No. 4-24455).

The sensor output selected by the multiplexer 29 is temporarily stored in a register 31 and supplied to an arithmetic processing unit 32. The arithmetic processing unit 32 calculates the waveform of the fault current (zero-phase current or short-circuit current at the time of ground fault) by a method described later, and further detects the phase and peak value. The phase and peak value of the fault waveform are supplied to an optical link (transmitter) 35 together with a signal indicating the time of occurrence of the fault (output of the clock 33), and are transmitted to an appropriate transmission line such as an overhead ground wire or an optical fiber cable 38. The data is transmitted to the master station or the general monitoring station 40 via the main station. The fault current measurement unit 100 surrounded by a chain line in FIG. 1 can be installed below the steel tower 8 as shown in FIG. Similarly, the fault current information detected by the fault current measuring unit 120 of another adjacent tower is transmitted to the master station 40 via an overhead ground wire or the like.

FIG. 2 is a functional block diagram showing details of the arithmetic processing unit 32. The fault current signal a such as a ground fault or short circuit output from the multiplexer 29 is supplied to the delay circuit (shift register) 101 and the arithmetic unit 103. On the other hand, the voltage signal d for phase reference output from the multiplexer 29 is supplied to the voltage zero cross detector 111. The function of the delay circuit 101 is achieved by reading out the signal waveform once stored in the register 31 in FIG. 1 after a predetermined delay time has elapsed, or by using a shift register. In the arithmetic unit 103, the fault current signal b delayed as described above and the fault current signal a directly supplied from the multiplexer 29 are added and subtracted so that the load current component is canceled, and the fault current is detected. This will be described with reference to FIG.

FIG. 3 is a waveform diagram for explaining the operation of the arithmetic processing section 32. FIG. 3A shows, for example, a signal from the ground fault sensor 20 for the upper line via the A / D converter 24 and the multiplexer 29. The ground fault current waveform directly supplied to the arithmetic unit 103, (b) is a delay circuit 1 obtained by delaying the waveform by three cycles.
01 is the output waveform. At the normal time before the ground fault occurrence time t2, zero-phase current does not flow through each transmission line.
Although the output of the ground fault sensor 20 should be zero, the effect of the load current of each phase wire on the sensor may not be balanced depending on the structure, layout, characteristics of the sensor, and layout of the transmission line. Often a small amplitude load current is detected. FIGS. 7A and 7B show this state.

In this example, since there is an integer cycle phase difference between the waveforms (a) and (b), when the difference between the two waveforms is calculated, the load current component before time t2 and three cycles from time t2 are calculated. The ground fault current components after the lapse of (delay time) are cancelled, and only the ground fault current components during three cycles from the ground fault occurrence time t2 are detected as shown in FIG. As is apparent, when the delay time is an integer cycle, the difference calculation between the waveforms (a) and (b) may be performed, but the delay time is 1 /
If it is an odd multiple of two cycles, waveforms (a) and (b) must be added. In short, the arithmetic unit 103
Is set so as to cancel the load current signal of small amplitude detected by the fault current detector when the transmission line is normal.

The waveform (c) is supplied to a peak value detector 105, a level comparison circuit 106, and a current zero cross detector 107. Note that the peak value detector 105 and the current zero cross detector 107 respond to the fact that the level of the signal waveform c of the fault current exceeds a predetermined value, and
6 do not operate until they generate outputs, or these outputs are suppressed.

The voltage zero cross detector 111 is supplied with the output waveform d of the phase reference voltage sensor 16 and supplies a pulse synchronized with the zero cross to the frequency divider 113. The frequency divider 113 has a function of determining a phase reference point B1 (FIG. 3) for measuring the phase of the fault current. In this embodiment, since the frequency divider is a 1/4 frequency divider, a pulse is generated every four periods of the waveform d, as shown by the solid line in FIG. A first and a second counter 117,
119 counts clock pulses CK from a clock oscillator (not shown). The output pulse of the frequency divider 113 is the first
The counter 117 is supplied to a reset terminal of the counter 117, and resets the counter 117 at every frequency division cycle (four cycles in this example) of the phase reference voltage. The output pulse of the frequency divider 113 is simultaneously supplied to the reset terminal of the second counter 119 via the reset delay circuit 115 and resets it. The reset delay circuit 115 includes the first counter 11
The second counter 119 is reset in the middle (preferably at the center) of the reset timing of FIG. 7, and generates a pulse as shown by a dotted line in FIG.

An accident occurs at time t2 in FIG.
When the amplitude of the signal waveform c of the fault current exceeds a preset reference level, the level comparison circuit 106 generates an output, whereby the peak value detector 105 and the current zero cross detector 107 are activated (or , Output enabled state). At time t4, when a zero cross of the fault current is detected, the detection signal is sent to the first and second counters 1 and 2.
17, 119. In the example of FIG. 3, the zero cross signal immediately after the output is generated by the level comparison circuit 106 is not used in consideration of the transient phenomenon of the fault current immediately after the occurrence of the accident. May be read. Both counters 117, 11
9 at time t4, the count values g and h are
8 and the larger count value is selected as the phase angle signal Tp and transferred to the data buffer 109. On the other hand, the peak value detector 105 detects the peak value P1 of the fault current, which is similarly transferred to the data buffer 109. The output of the level comparison circuit 106 is also applied to the clock 33, and the time of occurrence of the accident is transferred to the data buffer 109. The accident occurrence time, the fault current peak value, and the fault current phase angle are edited by the data buffer 109 so as to be suitable for transmission, and transmitted to the master station 40 via the optical link 35. The master station 40 compares the peak value and the phase angle of the fault current transmitted from two adjacent fault current measurement units of a certain transmission line, and when at least one of them is greater than or equal to a predetermined value, the above-mentioned 2 It is determined that there is an accident point between the two fault current measurement units, and its display, record,
Give an alarm.

Next, the principle of detecting a transmission line fault section according to the present invention will be described with reference to FIGS. These figures show the upper line of one end NGR (neutral point resistance ground)
FIG. 4 illustrates a detection state according to the present invention when a single-line ground fault occurs in either the upper line or the lower line in a four-line transmission line system including a lower line of a GR. Here, it is assumed that the ground fault sensors 11 to 13 for the upper and lower lines are installed as shown in FIG.

As shown in FIG. 5, when a ground fault occurs at the point X1 on the upper line, the power transmitting end SS1 and the power receiving end S
Ground fault currents I1 and I2 flow from S2 to ground fault point X1,
In the lower line, the fault current I3 flows toward the power transmitting terminal SS1 through the neutral point resistance ground NGR2 of the power receiving terminal SS3. Of the two detection points adjacent to each other with the ground fault point X1 therebetween, at the detection point F1 closer to the transmitting end SS1 than the fault point, the currents I1 and I2 flow in the same direction in the U1 and U2 phases of the upper line,
The R1 and R2 phases of the lower line are from the receiving end SS3 to the transmitting end SS.
1, a fault current I2 flows. These fault currents generate a magnetic field in the direction indicated by the arrow in FIG. 5, thereby inducing a positive current in each of the ground fault sensors 11 to 13.

Accordingly, the sum of the respective output currents of the ground fault sensors 11 and 12 and 12 and 13 becomes the output of the upper and lower line ground fault sensors 20 and 22.

On the other hand, the receiving ends SS2, S
At the detection point F2 on the S3 side, the currents I2 flow in opposite directions to the U1 and U2 phases of the upper line, and R1 and R2 of the lower line.
In the two phases, the fault current I3 flows in the same direction from the power receiving end SS3 to the power transmitting end SS1. As is apparent, the influence of the fault current I2 on the ground fault sensors 11 and 12 is cancelled, so that a magnetic field in the direction indicated by the arrow is generated in the sensor 12 mainly by the current I3, and a current is induced in the illustrated direction. . As described above, the output of the sensor 12 is added with the same polarity as the output of the sensors 11 and 13 to become the outputs of the upper and lower line ground fault sensors 20 and 22, respectively.

As is apparent from the above description, in the example of FIG. 5, the outputs of the ground fault sensors 20 and 22 between two points F1 and F2 adjacent to each other with the accident point in between have the same phase.
Failure detection cannot be performed by the conventional method. However, in the present invention, not only the phase of the fault current but also its magnitude (peak value) is compared, so that there is no difference in the lower line ground fault sensor 22, but as described in detail below, the upper line ground fault will be described. Sensor 20
It can be determined that the magnitude of the output current of the point F1 is twice or more that of the point F2, and a ground fault between the points F1 and F2 can be detected.

Assuming that the accident at the point X1 is a complete ground fault (ground fault resistance is 0), the value of the current T3 is determined by the resistance value of the NGR2. The current flowing from NGR1 to the upper line is I0
Then, I1 + I2 = I0 + 2I3. The output levels V (1) and V (2) of the upper line ground fault sensor 20 at the points F1 and F2 and the ratio between the two are expressed as follows. V (1) = α ｛K1 (I1 + I2) + K2 × 2I3｝ = α ｛K1 (I0 + 2I3) + K2 × 2I3｝ (1) V (2) = α ｛K1 (I2−I2) + K2 × 2I3｝ = αK2 × 2I3 (2) From the equations (1) and (2), V (1) / V (2) = K1 × I0 / K2 × 2I3 + K1 / K2 + 1 (3) where α is a constant and K1 , K2 are constants determined by the distance between each sensor and each phase transmission line. Normally, when each sensor is arranged as shown in FIG. 4 and Y-connection is established, since K1> K2, the expression (3) is larger than 2. Next, as shown in FIG. 6, when a ground fault occurs at the point X2 on the lower line, the ground fault currents I4 and I5 flow into the ground point X2 on the lower line, but do not flow on the upper line. Thereby, the upper and lower circuit ground fault sensors 20, 22 at the respective detection points F1, F2 on the power transmission end side and the power reception end side from the ground fault point.
Have opposite phases. Therefore, in this case, a ground fault between the points F1 and F2 can be detected by the phase comparison. In this case, since the outputs of the sensors 11 and 12 have opposite phases and are canceled, the output level output of the upper line ground fault sensor 20 becomes smaller.

FIG. 7 is a conceptual diagram for explaining the principle of short-circuit detection when a short-circuit accident has occurred in a single-ended power supply system four-line transmission line. Assuming that a short circuit has occurred between the U1 and V1 phases of the upper line at the point X3 of the transmission line, as will be easily understood, the short circuit currents Is1 and Is2 between the U1 and V1 phases and between the U2 and V2 phases respectively are shown in FIG. Flows like so. As described above, the short-circuit sensor 14 is arranged such that the extension of the longitudinal axis of the iron core intersects the electric wires V1 and V2 and is perpendicular to these. Therefore, the direction of the induced magnetic field caused by the current flowing through the electric wires V1 and V2 is perpendicular to the iron core of the short-circuit sensor 14, and no induced current is generated. At point F1 on the power transmission end SS1 side from the fault point X3, induced currents in the double arrow direction are generated in the short-circuit sensor 14 by the same-direction currents Is1 and Is2 of the electric wires U1 and U2. On the other hand, at the point F2 closer to the power receiving end SS2 than the fault point X3, the currents of the electric wires U1 and U2 are equal in magnitude and opposite in polarity.
Generates almost no induced current. Therefore, by comparing the peak value of the output of the short-circuit sensor at points F1 and F2 sandwiching the fault point X3, a short-circuit fault can be detected and the fault section can be specified.

In the above description, the detection signal is transmitted to the master station 40 via the overhead ground line 38. However, the detection signal may be transmitted by another appropriate method such as using a weak radio wave, or at each detection point. Display and record the abnormal occurrence time, fault current phase angle, peak value, etc., and compare the phase angle and peak value at the same occurrence time by patrol, and find the section where the difference is more than the reference value. It can also be determined that the section is an accident. The reference value for determining the occurrence of an accident is about 180 ° for the phase angle, 1 for the peak value of the current voltage,
It is desirable to set it to 5 to 2 times or more. The reference point of the phase angle measurement can be arbitrarily determined by appropriately selecting the frequency division ratio of the frequency divider 113, and can be the voltage zero crossing point after the occurrence of the abnormality. It is desirable to set the zero cross point. It will be easily understood that the present invention can be implemented by software using a one-chip microcomputer or the like without using the hardware configuration as shown in FIG.

[0029]

According to the present invention, the effect of each transmission line load current can be obtained simply by calculating the outputs of a plurality of magnetic sensors arranged at predetermined positions with respect to the transmission line, as in the case of a multi-circuit tower. In the case where the current cannot be completely canceled, the influence of each transmission line load current can be removed and the fault current can be detected reliably. Therefore, the design of the ground fault and short circuit sensors, the installation of these sensors on the steel tower and the margin of adjustment are improved, which is also useful for cost reduction. Further, both the phase angle and the peak value of the fault current obtained at the adjacent detection points are compared, and when at least one of the differences exceeds the reference value, the interval between the adjacent detection points is determined as the fault section. In addition, it is possible to reliably detect an accident that cannot be detected by the conventional method because no phase difference occurs.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a functional block diagram illustrating details of an arithmetic processing unit in FIG. 1;

FIG. 3 is a waveform diagram for explaining the operation of the arithmetic processing unit in FIG. 1;

FIG. 4 is a schematic diagram showing how various sensors used in the present embodiment are attached to a transmission line tower.

FIG. 5 is a conceptual diagram for explaining the principle of detecting a fault section of a ground fault according to the present invention.

FIG. 6 is a conceptual diagram for explaining the principle of detecting a fault section of a ground fault according to the present invention.

FIG. 7 is a conceptual diagram for explaining the principle of detecting a fault section in a short circuit accident according to the present invention.

[Explanation of symbols]

11 to 13: ground fault sensor 14, 15 ... short circuit sensor 1
6 Voltage sensor 29 Multiplexer 32 Operation processing unit 33 Clock 35 Optical link 38 Transmission line 4
0: master station 100, 120: fault current measuring unit 101:
Delay circuit 103: arithmetic unit 105: peak value detector
106: Level comparator 107: Zero current cross detector
108: High value selector 109: Data buffer 111
... voltage zero cross detector 113 ... frequency divider 115 ... reset delay circuit 117, 119 ... first and second counters

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01R 31/08-31/11 G01R 19/00-19/32 H02H 7/26

Claims (4)

(57) [Claims] (1) It is set at appropriate intervals along a transmission line.
Fault current detecting means disposed at the measurement point
N / 2 cycles of each output signal of the current detection means
(N is a positive integer) delay means for delaying, and the fault current detection
Output signal of the output means and the corresponding signal delayed by N / 2 cycles.
Each signal is canceled by each output signal in the normal state of the transmission line.
Means for adding and subtracting so as to generate a fault current signal,
The phase of the fault current signal at one detection point and
Peak value and fault current at the adjacent detection point
A method for calculating the difference between the signal phase and the peak value, respectively.
Step and at least one of the difference between the phase and the peak value is
When it is larger than the predetermined reference value, the two adjacent
Means for determining a fault section between the detection points, and the fault current
Phase measuring means for measuring the phase of the signal, wherein the phase measuring means comprises a current zero cross detector for detecting a zero cross point of the current signal to be measured, and a voltage for detecting a zero cross point of the voltage signal. A zero-crossing detector, a frequency divider that divides an output pulse of the voltage zero-crossing detector, a first counter that is reset by each output of the frequency divider, and the first counter that is reset by each output of the frequency divider. A second counter reset in the middle of the reset timing of one counter, a clock oscillator for supplying a clock pulse to the first and second counters, and reading in response to a zero cross point detection signal of the current zero cross detector characterized in that the larger among the first and the count value of the second counter, and and a high value selector for selecting as the phase signal to be measured current signal is
Transmission line fault section detection device. 2. The apparatus according to claim 1, further comprising a level comparing unit for generating an output when an amplitude level of the fault current signal exceeds a predetermined reference value, and detecting the zero crossing point until the level comparing unit generates an output. The reading of count values of the first and second counters in response to a signal is inhibited.
An apparatus according to claim 1 . 3. A fault current apparatus according to claim 1 or 2, wherein at least one of the short-circuit current and fault current. 4. The ground fault current detecting means detects the positions of the upper and lower first hexagons connecting the positions of the respective phase power lines of the upper line and the positions of the respective phase power lines of the lower line, which are suspended from the tower having four lines. The three earth fault sensors installed in the lower side of the second hexagon to be connected and connected in a Y-shape to each other, each of the short-to-earth sensors comprises an elongated core and a coil wound thereon. 4. The apparatus according to claim 3 , wherein the longitudinal direction is arranged so that a longitudinal direction thereof is perpendicular to each phase power line and is horizontal.